1. Technical Field
The presently disclosed subject matter relates to vehicular lighting assemblies such as headlamps, and in particular to a lighting assembly with a reflector made of a BMC (Bulk Molding Compound) resin, which can realize reductions in assembly steps and maintain its aesthetic appearance and performance.
2. Description of the Related Art
Recently, for example, a plastic member made of newly developed resins referred to as a BMC (Bulk Molding Compound) resin, or a mixture of an unsaturated polyester resin and glass fiber, has been developed. These plastic members provide enhanced heat resistances and thermal expansion coefficients which are almost equivalent to those of metallic members. Thus, it is now possible to employ these types of plastic members, for example, for a reflector in vehicle headlamps which can be formed as a paraboloid of revolution or a spheroid of revolution.
FIG. 1 shows a reflector 90 made of such a resin. In order to form the reflector 90 of the aforementioned resin, the resin is first formed into a shape to suit the reflector 90, such as a paraboloid of revolution or a spheroid of revolution. Then, to enhance the smoothness of the portion used as a reflecting surface of the reflector 90, an appropriate amount of an undercoating resin which has a high viscosity is dispensed onto the inner surface of the reflector 90, and the reflector 90 is then rotated at a high speed.
This allows the undercoating resin to be formed on the inner surface of the reflector 90 as an undercoat film 91 which has a uniform thickness with almost no surface asperities. The undercoat film 91 is then sufficiently dried and hardened with the aforementioned smoothness maintained.
The undercoat film 91 thus obtained, for example, can have a substance such as aluminum or silver deposited thereon in an appropriate thickness by vacuum deposition or the like, thereby forming a mirror surface 92 to provide a reflection mirror 94. Then a light source 93 is placed at a focus of the reflector 90. When the light source 93 is turned on, the reflection mirror 94 reflects light from the light source 93 as collimated beams.
It should be noted that the reflector 90 can be readily shaped as desired when molded of the BMC resin as described above. Taking advantage of this fact, a lighting assembly holder portion 95 having a high-beam reflection mirror 94 may be formed as shown in FIG. 2. The lighting assembly holder portion 95 may be integrally provided with an aiming unit 80, discussed later, a low-beam reflection mirror 97, and the like. In this instance, the low-beam reflection mirror 97 has a reflector 96 and is integrated with an adjusting nut attachment 82 or part of the aiming unit 80. In this manner, a headlamp 70 is formed in an integrated configuration and thus can be attached to vehicles with improved assembly operation (see, for example, Japanese Patent Application Laid-Open No. 2005-310386).
The reflectors 90 and 96 formed of the BMC resin as described above will naturally have a performance as required of the reflectors 90 and 96 in terms of heat resistance or the like. However, a headlamp 70 equipped with these reflectors 90 and 96 would have to be provided with an additional device, or the so-called aiming unit 80 mentioned above, which can be adjusted so as to provide illumination in a prescribed direction when attached to the vehicle body.
In this case, even the BMC resin which has a high heat resistance and a high hardness for resin would lack strength for certain aspects of the headlamp. Accordingly, a metallic member has to be used to separately form those portions that are subject to great heat or stress, such as ball joints 81 of the aiming unit 80 or a connection between the ball joints 81 and the lighting assembly holder portion 95. Then, these metallic portions have to be integrated with the lighting assembly holder portion 95 by screws or the like.
In addition to this, when sliding portions such as hinges or screws are made of the BMC resin, this would cause the glass fiber added to the resin to fly away in the form of powder during sliding. The flying glass fiber would adhere to the mirror surface 92 of the reflectors 90 and 96, causing degradation in appearance and occurrence of glare. Accordingly, from this point of view, those portions such as the aiming unit 80 that require strength have to be formed of a metallic member. This causes the aiming unit 80 to overlap the low-beam reflection mirror 97 when attached to the same position on the lighting assembly holder portion 95, resulting in the entire structure being made more complicated and in an increase in costs.